1. Field of the Invention
The present invention relates to a semiconductor module, and, more particularly, to a wafer level type semiconductor module having a light permeable cover.
2. Description of the Related Art
A sensor device, which is represented by a CMOS image sensor, is used in a portable device, such as a mobile phone, to take an image. The sensor device for taking an image, constituted by a camera unit including a lens, an image processing chip, a semiconductor chip of a sensor main body, a substrate, and a housing, is assembled in the portable device.
According to high performance and slimness of the portable device, miniaturization of the camera unit is being strongly requested. For this reason, by camera unit manufacturers, downsizing of the sensor, integration of the lens with the semiconductor chip, and so on are performed.
The downsizing of the sensor is typically achieved by a chip size package (CSP). Japanese Patent Application Publication No. 2007-129164 discloses a semiconductor module for optical apparatuses using a wafer level chip size package (W-CSP), which is a kind of CSP. In this semiconductor module, a solid state imaging device, which is a semiconductor chip, is covered by a light permeable cover, an electrode pad disposed at an outer circumferential region of the solid state imaging device is electrically connected to an external connection terminal provided at the back of the solid state imaging device (the side opposite to the light permeable cover) via a re-wire in a through hole. A lens unit having a lens is fixed on the light permeable cover. Light, incident upon the lens, passes through the light permeable cover and reaches an effective pixel region (a light receiving device portion) of the solid state imaging device, where an electric signal created by a photoelectric conversion device is extracted from the external connection terminal provided at the back of the solid state imaging device.
In the conventional CSP structure disclosed in Japanese Patent Application Publication No. 2007-129164, however, light is unnecessarily introduced from the side of the light permeable cover, and the introduced light reaches the light receiving device. Therefore, it is not possible to achieve predetermined performance of the sensor. Also, in a semiconductor module constructed such that the lens unit is fixed to the light permeable cover as disclosed in Japanese Patent Application Publication No. 2007-129164, if a thickness error of the light permeable cover, or an adhesion thickness error between the lens unit and the light permeable cover, exists, the distance between the lens and the front of the semiconductor chip may not be appropriately adjusted, a focusing range may deviate from a desired level, or no focus is adjusted at all.